The Mound Builders used metal tools, and were probably metal builders. Based on that information I would say the answer is B.Copper, because copper is a metal.
The correct answer to this open question is the following.
Although there are no options attached we can say the following.
The music of the southeast reflected the many cultures of people who settled there in that this music expressed the identity, culture, history, and belief systems of the black people who were slaves and worked in the large southern plantations growing crops.
Music genres such as the Blues, Jazz, and Gospel music originated in the South, in churches, and in places where black people gather together to hang out.
These music genres spread throughout the United States when the blacks emigrated to Chicago and other places in the North. They started to record their music and radio stations played their songs that white people loved. This music spread throughout the world when records companies started to export this music and promoters hired these artists to perform in live concerts.
